Ok, these are things I've not done before. So bear with me!

The local desktop is the one connected to the router wirelessly that I'm trying to access via Rdesktop, and this has a false IP designated by the router? Meaning the router has it's own IP, which differs to the internet connection IP?

I know nothing of ssh tunnel, however I could possibly do the second option. What do I need to do to make this happen?

I apologise for the newb questions.